Heat sealable valve type bag



J. B. PATON HEAT SEALABLE VALVE TYPE BAG May 10, 1955 Filed Sept. 9, 1954 2 Sheets-Sheet '1 Flt-LING SPoUT- INVENTOR,

c/Gmas 5. Pafofl BY 2 May 10, 1955 J. B. PATON HEAT SEALABLE VALVE TYPE BAG 2 Sheets-Shem 2 Filed Sept. 9, 1954 SPaur BEING WI THDRA WM l QQ'O'O 'o IN VEN TOR. dames B. Pafon M #M ATTORNEYS Patented May 1 0,

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HEAT SEALABLE VALVE TYPE RAG James B. Paton, Dearborn, Mich assignor to Paton- {Ihandier Process Company, Detroit, Mich a registered partnership Appiication September 9, 1954, Serial No. 454,927

3 Claims. (Cl. 22962.5)

This invention relates to the packaging of fiuid materials such as powders, granular materials and liquids and, more particularly, to bags for the packaging of such materials which are fabricated from sheet material that is either thermoplastic itself or has a thermoplastic coating and that is heat sealed in a particular manner to form the bags to provide for valve-bag action when the bags are inserted on a filling spout of a conventional spout type bag packer.

So-called valve bags are employed for packaging many granular and powdered materials such as cement, fertilizer, etc., the bags in these instances being fabricated from several thicknesses of heavy paper which are sewed together to provide a valve type opening at one of the corners of the bag through which can be inserted the elongated nozzle of a packing machine to feed the material into the interior of the bag. When the bag is full it is withdrawn off the nozzle and the folds of the paper which form the valve are squeezed upwardly by the content material to close the opening through which the nozzle was originally inserted.

While the use of paper for bagging is widespread, many materials preferably should be packaged in moistureproof material such as thermoplastic resinous films and, in some instances, it it were possible rapidly and easily to package some types of material in a bag made of a selected thermoplastic material, the thermoplastic material of which the bag is formed would not be incornpatible in the formulation or compound in which the content material is used so that the bag would not need ever to be opened after it once had been packed. As an example of such a utilization of a thermoplastic bag, carbon black employed as an ingredient in the formulation of rubber for automobile tires can be packaged in a package made of polyethylene film in measured amounts, say, one-quarter, one-half, one or five pounds each, and the carbon black can be added to the Banbury mixer in the rubber formulation room by merely tossing the closed polyethylene bags of carbon black into the mixer. Such a procedure is highly advantageous because the bags of carbon black would never need to be opened in the formulation room, thus obviating the possibility of the carbon black spreading around the room and eliminating a problem of clean up or control.

The use of thermoplastic fiim as a material for the formation of bags in the packaging of powdered substances is known in many arts, but for the most part the operations have included the formation of an open mouthed bag, the deposition of the powder in the bag and the subsequent sealing of the bag; or the formation of bags continuously from a tube of material with the tube formed longitudinally around a filling spout which intermittently charges the bags after their lower seals are formed. In either case no way is provided to prevent the content material from adhering or clinging to those portions of the bags which are to be heat sealed for closing. Contamination of the areas to be heat sealed I operations or simultaneously by spaced dies.

by the content material very seriously interferes with effective sealing of the bags.

It is an object of this invention to provide a bag fabricated from a heat scalable film which is presealed to provide a valve type bag, the presealed areas and the bag design resulting in the formation of a bag incorporating an automatic valve and means for preventing the contamination of the final sealed area by the content material.

It is another object of this invention to provide a bag easily fabricated from a standard gusseted tubing continuously fabricated by an extrusion die machine from a thermoplastic resinous material.

A still further object of this invention is to provide a bag having the advantages of the film from which it is formed, such as ease of fabrication, heat scalability, impermeability to air or moisture, and also having the advantage of a valve-bag design.

More specific objects and advantages will be apparent from the specification which follows and fromthe drawings, in which:

Fig. l is a view in elevation with parts broken away showing a bag embodying the invention in filling position on the spout of a conventional spout type packing machine.

Fig. 2 is an enlarged horizontal sectional view taken along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary vertical sectional view taken along the line 33 of Fig. l.

Fig. 4 is a fragmentary view in perspective and on a greatly enlarged scale of an upper corner of a bag embodying the invention, and illustrating the formation of the sealed areas by which the valve-bag feature of the invention is provided.

Fig. 5 is a fragmentary view in section similar to Fig. 2 but on a smaller scale and showing the filling spout being withdrawn from a bag embodying the invention.

Fig. 6 is a view in perspective of a bag embodying the invention after it has been filled and sealed.

Fig. 7 is a fragmentary view in elevation of the upper corner of a bag embodying the invention and illustrating a modification in the method of sealing the bag after the withdrawal of the sealing spout.

A bag embodying the invention and generally indicated at It in Fig. l, is fabricated from a gusseted tubing of appropriate transverse dimension, the tubing being seamless and consisting of a thin film of a thermoplastic resinous material. Any thermoplastic resinous sheet material or plastic sheet material having a heat scalable coating or other sheet material, for example,

wax paper, may be fabricated to construct a tube having a generally planar front face 11, aback face 12 (Fig. 2) and infolded gussets 13 and 14 at its sides. Gusseted tubing of this type is available as a commercial article of manufacture in many types of sheet materials and in many sizes of tubing and thicknesses of material.

The first step in the formation of a bag embodying the invention consists in cross sealing the bag as at 15, for example (Figs. 1 and 6) to close the bottom of the bag. The cross seal 15 may be formed simultaneously with a top cross seal 16 to close the top of the bag if desired by sealing a wider transverse area of the tubing from which the bag is formed and then cutting across the sealed area or the tubing may first be cut into lengths and then the top and bottom seals formed in successive In any event the cross seals 15 and 16 extend all the way across the tubing from which the bag it) is formed. If the material is thermoplastic itself, the seals are merely fused areas of the material. If the material is not thermoplastic, but is coated with a heat scalable substance as, for example, cellophane coated with heat sealable waxes or paper coated with wax, metal foil coated with a fusible resin or varnish, or any other sheet material having a heat sealable coating, the heat applied at the time of formation of the seals 15 and 16 adheres the several folds of sheet material at the gussets 13 and 14 and the front and back 11 and 12 together in the areas of the bottom seal 15 and top seal 16.

At the time of formation of the top seal 16 or in a subsequent step, a partial seal 17 also is formed near an upper corner of the bag 10 and extending across the bag from one edge inwardly to say approximately the center of the bag. The seal 17 is spaced from the seal 15 leaving an unsealed area generally indicated at 18. Simultaneously with the formation of the seal 17 or in an operation performed subsequently thereto, the innermost fold of the gusset 14, indicated at 19, is slit transversely between the seals 16 and 17 so that the corner of the bag 10 may be flexed slightly as in Fig. 4 to provide a passageway 20 leading inwardly between the top seal 16 and the partial seal 17 and communicating with the interior of the bag 10. Slitting the edge 19 of the gusset 14 provides two edges 21 and 22, one at each side of the passageway 20.

The operations just described result in the formation of a plastic bag as depicted in Figs. l-4, inclusive. All of the three seals 15, 16 and 17 can be simultaneously formed by one sealing operation. It is not necessary even to slit the edge 19 of the gusset 14 at the time of the formation of the seals 15, 16 and 17 since the gusset edge 19 can easily be slit by a lance formed at the front end of a filling spout. 23 of such size as to fit through the passageway 20 and extend beyond the partial seal 17. For example, if the three seals 15, 16 and 17 are simultaneously formed and the gusset edge 19 is not slit at formation of the bag, the bags remain hermetically sealed and thus clean until the time of their actual filling. the other hand, the gusset edge 19 is slit at the time of formation of the seals 15, 16 and 17, the filling spout 23 need not be provided with a lance on its forward end, under these conditions, the Spout 23 can have a rounded forward end such as that shown in the drawings so that the bags will not inadvertently be damaged by the lance otherwise needed to slit the gusset edge 19.

Conventional spout type packing machines usually are provided with settler chairs, shown in broken lines in Fig. l and indicated by the reference number 24the settler chair not constituting a part of the instant invention but being a conventional structural element like the spout 23.

When it is desired to fill a bag of the invention it is thrust over the end of the filling spout 23, either having its gusset edge 19 lanced at the time or having a previously lanced gusset edge 19, and after being thrust fully onto the spout 23 the packing machine is energized to feed the content material through the spout 23 and into the interior of the bag 10 as indicated by the arrows in Fig. 1. After the bag is filled, this being determined, for example, by weight or volumetric control mechanism, the bag is withdrawn off the spout 23 and, as illustrated in Fig. 5, the edges 21 and 22 of the slit gusset edge 19 are wiped along the edges of the spout 23, being squeezed quite tightly against the spout 23 by the weight of the content material tending to pull the bag 10 downwardly. This wiping action prevents the adherence of any small quantities of content material to the exterior of the spout 23 If, on

4 and its consequent deposition on the portions of the spaced wings of the gusset 14 generally indicated at 25 in Fig. 4, and which form portions of the walls of the passageway 20.

After the spout 23 is completely withdrawn from the bag, pressure of the content material as indicated particularly in Fig. 6, tends to squeeze the bag walls together across the passageway 20 and, if desired, particularly in some instances where contamination of the content material is to be prevented or where the content material is of such nature that escape of even any minute quantity from the bag is to be prevented, the passageway 29 may be sealed by a short transverse closing seal 26 (Fig. 6).

If the content material of the bag is such that dusting of the surfaces 25 is impossible to prevent even by the wiping action of the edges 21 and 22, for example, if the material is an exceedingly fine powdered material which is Waited onto the surfaces by the air currents set up when the bag is drawn off the spout, it may be desirable to seal the passageway 20 in the manner illustrated in Fig. 7. In this case a sealed area 27 is employed to close a folded-over corner generally indicated at 28 which is folded across'the passageway 20, the thicknesses of the front surface 11, the two surfaces 25 of the gusset 14 and the rear surface 12 being doubled over upon each other and all fused or sealed together by the single seal 27. This manner of forming the closing seal 27 positively prevents interference with the seal by any powder or dust on the surfaces 25 because the bag is etfectively sealed by the two touching portions of the front face 11 being sealed together since the fold insures the closing of the passageway 20 through the gusset 14.

Having described the invention, 1 claim:

1. A package for powdered and the like materials, said package having opposed front and back, gusset-like reentrant fronts of material integral with said front and back and forming sides for said package connecting said front and back, a bottom seal and a top seal closing said front and back together and adhering said front and back and said gusset fronts together, and a filling tube forming seal extending part-way across said package from one edge thereof inwardly and spaced from said top seal, there being an unsealed area between said top and tube forming seal extending from one edge of said package across above said tube forming seal, the space between said front and back in such unsealed area being in communication with the interior of said package and adapted to receive a filling machine spout inserted therein through the side of said package located above said tube forming seal.

2. A package according to claim 1 in which said back and front and said gusset folds all consist of heat sealable sheet material.

3. A package according to claim 2 in which the sheet material is thermoplastic resinous film.

References Cited in the file of this patent UNITED STATES PATENTS 1,861,995 Williams June 7, I932 2,119,895 Sutton June 7, 1958 2,682,902 Metzger July 6, 1954 2,696,342 Toborg Dec. 7, l954 2,697,531 Hood Dec. 21, 1954 

